(a) Technical Field
The present invention relates to a photosensor and, more particularly, to a display device including a photosensor.
(b) Disclosure of Related Art
Examples of flat panel display devices include liquid crystal display (LCD) devices, organic light emitting diode (OLED) display devices, and plasma display panel (PDP) devices. The LCD devices are the most widely used flat panel display. An LCD device generally includes two panels and a liquid crystal layer having dielectric anisotropy disposed between the two panels. In an LCD device, an electric field is applied to the liquid crystal layer and the electric field is controlled to adjust transmittance of light passing through the liquid crystal layer, thereby displaying images.
Since the LCD device is not a self-emissive display device, it includes a backlight unit for supplying light to the two panels. However, the backlight unit consumes a significant amount of power, and thus it is suggested that a photosensor be employed to control the backlight unit. The photosensor is particularly suited for use in portable devices such as mobile phones and notebook computers.
Photosensors may be integrated into an LCD device for sensing external light to increase light efficiency. The photosensor includes amorphous silicon that may generate leakage current in response to external light. The LCD device senses the leakage current to control itself.
However, it is difficult to exactly sense the amount of external light. Therefore, for example, a transflective LCD device operating in a transmissive mode and a reflective mode may undesirably operate in the transmissive mode under a strong external light to consume significant power for turning on a backlight unit. The transflective LCD device may display a degraded image due to the inconsistency of the external light and the operating mode of the LCD device.
In addition, the temperature of peripheral circumstance may cause the photosensors to fail in sensing the exact amount of the external light. Furthermore, the external light illuminated into a display panel may also affect the operation of the photosensors.